Optical storage apparatus

ABSTRACT

A division test write processing unit is provided and a test writing process for deciding an optimum light emitting power by executing a test writing on a medium is divided into a plurality of division test writing processes. When an upper command is received, in the division test write processing unit, a division control unit skips to a division executing unit locating at the head of the processes which are not yet executed among a plurality of division executing units and allows the dividing processes of the test writing to be executed for a predetermined time.

This is a division of application Ser. No. 09/027,260, filed Feb. 20,1998, now U.S. Pat. No. 6,275,462.

BACKGROUND OF THE INVENTION

The invention relates to an optical storage apparatus using a removablemedium such as magnetooptical cartridge, phase-change type optical disk,DVD-RAM, or the like and, more particularly, to an optical storageapparatus for executing an access of a command while deciding an optimumlight emitting power by a test writing on a medium when receiving a hostcommand.

An optical disk has been highlighted as a storage medium serving as acore of multimedia which has rapidly been developed in recent years. Forexample, in case of an MO cartridge of 3.5 inches, in addition toconventional medium of 128 MB, medium of a high-density recording of 540MB or 640 MB has also been being presented in recent years. In the MOcartridge which is used in an optical disk drive, a ZCAV recording (zoneconstant angular velocity recording) in which a medium track is dividedinto zones and the number of sectors is set to be equal every zone isused. The medium of 128 MB uses the recording method of a pit positionmodulation (PPM). It is sufficient that the light emitting power changesat three stages of a reading power, an erasing power, and a recordingpower. On the other hand, the media of 230 MB, 540 MB, and 640 MB usethe recording method of a pulse width modulation (PWM) in order to raisea recording density. In the PWM recording, it is necessary to change thelight emitting power at four stages of the reading power, the erasingpower, a first writing power, and a second writing power. In the PWMrecording of a medium of a direct overwrite corresponding type whichdoesn't need the erasing operation, it is necessary to change the lightemitting power at four stages of the reading power, an assisting power,the first writing power, and the second writing power.

However, in the recording medium of a high density such as 540 MB or 640MB in which the PWM recording is performed, a margin of an optimumwriting power of a laser diode which is used for medium recording isnarrow. When a temperature of the medium changes, the optimum writingpower changes. The optimum writing power also changes depending onmanufacturing conditions of the medium or a difference of writingperformance of the optical disk drive. That is, in case of recording bya predetermined writing power which was unconditionally determined at adesigning stage, the writing power largely deviates from the actualoptimum writing power and a case where the recording operation cannot beexecuted occurs, so that there is a problem that writing and readingperformance deteriorates.

SUMMARY OF THE INVENTION

According to the invention, there is provided an optical storageapparatus constructed in a manner such that even when there is adifference of performance of apparatuses or manufacturing conditions ofmedia or when an apparatus temperature changes, an optimum writing powercan always be set and, further, even when it takes a long time for aprocess to set the optimum power, an error due to a time-out doesn'toccur for an upper apparatus.

An optical storage apparatus of the invention comprises: a tightemitting power adjusting unit for adjusting a light emitting power of alaser diode which is used for recording and reproduction of a medium;and a division test writing processing unit for dividing a test writingprocess to an optimum light emitting power by executing a test writingon the medium into a plurality of processes and for sequentiallyexecuting the divided processes each time an upper command is received.By the division test writing process as mentioned above, a series oftest writing processes accompanied with the erasing, writing, andreading operations (in the direct overwrite corresponding type mediumwhich doesn't need the erasing operation, the test writing process forwriting and reading) when the upper command is received are divided intoa plurality of processing stages and are sequentially executed. Evenwhen the apparatus temperature rapidly changes and the optimum powerremarkably deviates from the default power which has initially been setand it takes a long time up to the end of the test writing operation tofind the optimum power, since the processes are distributed andexecuted, a time-out for the upper command doesn't occur and therecording and reproducing operations can be executed as much as possibleeven when the power is deviated from the optimum power, so that theapparatus performance is improved.

An optical storage apparatus of the invention comprises: a lightemitting power adjusting unit for adjusting a light emitting power of alaser diode which is used for recording and reproduction of a medium;and a division test writing processing unit for dividing a test writing,process to determine an optimum light emitting power by executing a testwriting on the medium into a plurality of processes and for sequentiallyexecuting the divided processes each time an upper command is received.By the division test writing process as mentioned above, a series oftest writing processes accompanied with the erasing, writing, andreading operations (in the direct overwrite corresponding type mediumwhich doesn't need the erasing operation, the test writing process forwriting and reading) when the upper command is received are divided intoa plurality of processing stages and are sequentially executed. Evenwhen the apparatus temperature rapidly changes and the optimum powerremarkably deviates from the default power which has initially been setand it takes a long time up to the end of the test writing operation tofind the optimum power, since the processes are distributed andexecuted, a time-out for the upper command doesn't occur and therecording and reproducing operations can be executed as much as possibleeven when the power is deviated from the optimum power, so that theapparatus performance is improved.

The division test writing processing unit comprises a division executingunit and a division control unit. The division executing unit dividesthe test writing process into a plurality of processes and executes.When receiving the upper command, the division control unitdiscriminates about the necessity of the test writing. When it isdetermined that the test writing is needed, the division control unitskips to the head of the unexecuted processes in the division executingunit and allows the dividing process of the test writing operation to beexecuted for a predetermined time. Each time one of the divisionexecuting processes is finished, the division control unit preserves theprocessed number and a processing result. When the elapsed time from thestart of the dividing process is shorter than a predetermined time, theprocessing routine advances to the next dividing process. When apredetermined time elapses, the division control unit interrupts theprocesses and waits for a next upper command. When the elapsed time fromthe preceding dividing process by the division executing unit to thepresent dividing process is longer than a predetermined time, thedivision control unit cancels the processed numbers and processingresults of up to the preceding time and again executes the dividingprocesses from the beginning. When the interrupting time of the dividingprocess becomes too long, there is a case where the optimum powerfluctuates due to the temperature change or the like during theinterrupting time. In this case, a more accurate optimum power is foundby again executing the processes from the beginning.

For example, the division executing unit is constructed by:

a first division executing unit for setting a predetermined initiallight emitting power (default value) at the first time and for setting alight emitting power obtained by changing the initial light emittingpower by every predetermined value at the next and subsequent times;

a second division executing unit for erasing a test area of a medium bythe set light emitting power;

a third division executing unit for writing a predetermined test patterninto the erased test area;

a fourth division executing unit for reading out the test patternwritten in the test area; and

a fifth division executing unit for deciding the number of times of datadissidence (error rate) by comparing the test pattern with the read-outpattern and for calculating the optimum light emitting power on thebasis of the number of times of dissidence obtained by the test writingoperations of a plurality of times by the first to fourth divisionexecuting units.

In this instance, as for the medium of the direct overwritecorresponding type which doesn't need the erasing operation, thedivision executing unit is constructed by:

a first division executing unit for setting a predetermined initiallight emitting power (default value) at the first time and for setting alight emitting power obtained by changing the initial light emittingpower by every predetermined value at the next and subsequent times;

a third division executing unit for writing a predetermined test patterninto a test area;

a fourth division executing unit for reading out the test patternwritten in the test area; and

a fifth division executing unit for determining the number of times ofdata dissidence (error rate) by comparing the test pattern with theread-out pattern and for calculating an optimum light emitting power onthe basis of the number of times of dissidence obtained by the testwriting operations of a plurality of times by the first to fourthdivision executing units.

The division control unit has an-elapsed time control unit forcontrolling by discriminating whether the division test writing processis performed or not on the basis of the elapsed time from apredetermined start timing of the apparatus. In this instance, as astart timing, in addition to the timing when the medium is loaded intothe apparatus, a recovery timing from a sleeping mode in which a servounit and a spindle motor are stopped, and the like are also included.The elapsed time control unit effectively operates for a period of timeuntil the elapsed time from the start timing such as a loading of themedium or the like reaches a predetermined time, thereby controlling aplurality of division executing units. That is, a temperature in theapparatus rapidly rises and a distribution of the internal temperaturesbecomes fairly uneven for a period of time until about two to threeminutes elapse after the medium was loaded in association with thepower-on of the apparatus, so that the apparatus is in a state in whicha detection value of the temperature sensor cannot be guaranteed.Therefore, the necessity of the test writing is discriminated on thebasis of the elapsed time in a manner such that when the elapsed timefrom the medium loading is short, the test writing is executed at a highfrequency and, when the elapsed time becomes long and the temperaturebecomes stable, the frequency of the test writing is reduced. That is,the elapsed time control unit decides the optimum light emitting powerby executing a plurality of test writing processes in a lump by thefirst upper command and also sets a valid time Tv when it is unnecessaryto adjust the optimum light emitting power on the basis of the elapsedtime at that time. After the first time, the elapsed time control unitinhibits a division test writing for the upper command until apredetermined rate time of the valid time Tv elapses, and executes thedivision test writing in response to the upper command for a period oftime until the valid time Tv from the predetermined rate time. Theelapsed time control unit sets the valid time Tv so as to be graduallyextended in proportion to the elapsed time after the start timing. Theelapsed time control unit inhibits the division test writing for a timezone that is shorter than, for example, 90% of the valid time andpermits the division test writing for a time zone exceeding 90% of thevalid time. When the elapsed time exceeds the valid time Tv during theexecuting stage of the division test writing, since there is apossibility that the optimum power is remarkably deviated, the elapsedtime control unit executes the remaining division test writing in a lumpby a next upper command in this case.

On the other hand, the division control unit has a temperature changecontrol unit for controlling by discriminating whether the division testwriting process is executed or not on the basis of a change in apparatustemperature. The temperature change control unit operates after that apredetermined time during which the elapsed time control unit operates,for example, 160 seconds elapses from the start timing of the apparatusand the temperature in the apparatus became stable. The temperaturechange control unit detects the temperature in the apparatus everypredetermined time and, when a temperature difference between thepreceding detection temperature and the present temperature exceeds apredetermined temperature, for example, 3° C., allows the dividingprocess to be executed. When the temperature difference exceeds an upperlimit temperature, for example, 4° C. that is higher than apredetermined temperature of 3° C., during the interruption of thedividing process, there is a possibility that the optimum power largelychanges. Therefore, in this case, the temperature change control unitallows the division executing unit to execute the dividing processes ina lump. When the temperature difference between the preceding andpresent dividing processes exceeds a predetermined temperature, forexample, 2° C. during the dividing processes by the division executingunit, there is a possibility that the interrupting time in the dividingstate is too long and the optimum power remarkably changes. Therefore,the temperature change control unit cancels the processed numbers andprocessing results up to the preceding time and again executes thedividing processes from the beginning.

According to the invention, a medium is divided into a plurality ofareas in the radial direction, for example, into an inner rim area, anintermediate area, and an outer rim area and the processes by thedivision test writing processing unit and the division control unit areindependently executed every area. This is because the CAV is used forthe rotation control of the medium and peripheral speeds in the radialdirection of the medium differ, so that laser powers for heating themedium also differ. Therefore, the optimum power of each area is foundby dividing the medium into, for example, three areas and independentlyexecuting the division writing test every area. Since the medium isdivided into a plurality of zones in the radial direction, a pluralityof zones are divided into groups every plurality zones in the radialdirection, thereby dividing into a plurality of areas. The processes bythe division test writing processing unit and the division control unitare independently executed every area.

Further, according to another embodiment of the invention, it is alsopossible to sequentially execute the division test writing processes bythe division test writing processing unit in accordance with apredetermined time schedule of an elapsed time without depending on anupper command. When a temperature change of a predetermined value ormore occurs, it is also possible to sequentially execute the divisiontest writing processes by the division test writing processing unitwithout depending on the upper command.

The above and other objects, features, and advantages of the presentinvention will become more apparent from the following detaileddescription with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are block diagrams of an optical disk drive according tothe invention;

FIG. 2 is an explanatory diagram of an internal structure of anapparatus in which an MO cartridge has been loaded;

FIG. 3 is a block diagram of a laser diode control circuit in FIGS. 1Aand 1B;

FIGS. 4A to 4J are time charts of signals, light emission currents,subtraction currents, and a monitor current by the PWM recording of theinvention in a medium of a direct overwrite corresponding type;

FIGS. 5A to 5J are time charts of signals, light emission currents,subtraction currents, and a monitor current by the PPM recording of theinvention in the medium of the direct overwrite corresponding type;

FIGS. 6A and 6B are functional block diagrams of a test writing processof the invention which is realized by an MPU in FIG. 1;

FIGS. 7A and 7B are explanatory diagrams of the test writing process ofthe invention according to a time schedule after the medium was loaded;

FIG. 8 is an explanatory diagram of a valid time setting table which isused for the test writing process of the invention;

FIG. 9 is a characteristics diagram of light emitting powers and thenumber of errors obtained by a division test writing process in order tocalculate an optimum light emitting power of the invention;

FIG. 10 is an explanatory diagram of a default erasing power table inFIG. 6;

FIG. 11 is an explanatory diagram of a default writing power table inFIG. 6;

FIG. 12 is an explanatory diagram of a temperature correctioncoefficient table in FIG. 6;

FIG. 13 is a schematic flowchart for the whole operation of theapparatus including a division test writing of the invention;

FIG. 14 is a flowchart for a valid time test writing process fordiscriminating the necessity of a test writing on the basis of a validtime in FIG. 13;

FIGS. 15A and 15B are detailed flowcharts for the division test writingprocess in FIG. 14;

FIGS. 16A and 16B are detailed flowcharts for the division test writingprocess in FIG. 14 subsequent to FIG. 15B;

FIG. 17 is a flowchart for a calculating process of an optimum power inFIGS. 16A and 16B;

FIGS. 18A and 18B are flowcharts for a batch test writing process shownby extracting a processing portion in a case where a batch executionflag is turned on in the division test writing process of FIGS. 15A,15B, 16A, and 16B; and

FIG. 19 is a flowchart for a temperature change test writing process todiscriminate the necessity of the test writing on the basis of atemperature change in FIG. 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[Apparatus construction]

FIGS. 1A and 1B are circuit block diagrams of an optical disk drive asan optical storage apparatus of the invention. The optical disk drive ofthe invention is constructed by a control unit 10 and an enclosure 12.The control unit 10 has: an MPU 14 for executing a whole control of theoptical disk drive; an interface controller 16 for transmitting andreceiving commands and data to/from an upper apparatus; an optical diskcontroller (ODC) 18 having functions of a formatter and an ECC which-arenecessary to read and write data from/to an optical disk medium; and abuffer memory 20. An encoder 22 and a laser diode control circuit 24 areprovided as a writing system for the optical disk controller 18. Acontrol output of the laser diode control circuit 24 is supplied to alaser diode unit 30 provided on the enclosure 12 side. The laser diodeunit 30 integratedly has a laser diode and a photosensing device formonitoring. As an optical disk for recording and reproducing by usingthe laser diode unit 30, that is, as a removable MO cartridge medium,any one of MO cartridge media of 128 MB, 230 MB, 540 MB, and 640 MB and,further, direct overwrite corresponding type media of 540 MB and 640 MBcan be used in the embodiment. With respect to the MO cartridge mediumof 128 MB among them, a pit position recording (PPM recording) forrecording data in correspondence to the presence or absence of a mark onthe medium is used. A recording format of the medium is based on ZCAVand is set to one zone in case of the 128 MB medium and to ten zones incase of the 230 MB medium. On the other hand, with respect to the MOcartridge media of 230 MB, 540 MB, and 640 MB, a pulse width recording(PWM recording) in which edges of a mark, namely, front and rear edgesof a mark are made correspond to data is used. The PWM recording is alsocalled a mark recording or an edge recording. A difference between thestorage capacities of 640 MB and 540 MB is caused by a difference ofsector capacities. When the sector capacity is equal to 2 kB, thestorage capacity is equal to 640 MB. On the other hand, when the sectorcapacity is equal to 512 B, the storage capacity is equal to 540 MB. Therecording format of the medium is based on the ZCAV and is set to 10zones in case of the 230-MB medium, 11 zones in case of the 640-MBmedium, and 18 zones in case of the 540-MB medium. As mentioned above,the optical disk drive of the invention can cope with the MO cartridgeshaving the storage capacities of 128 MB, 230 MB, 540 MB, and 640 MB and,further, the medium cartridges of the direct overwrite correspondingtype. When an MO cartridge is loaded into the optical disk drive,therefore, an ID region of the medium is first read, the kind of mediumis recognized by the MPU 14 from the pit interval, and the recognitionresult is notified to the optical disk controller 18. Consequently, incase of the medium of 128 MB or 230 MB, a formatting processcorresponding to the PPM recording is executed. In case of the medium of540 MB or 640 MB, a formatting process according to the PWM recording isexecuted.

As a reading system for the optical disk controller 18, a decoder 26 anda read LSI circuit 28 are provided. A photosensing signal of a returnlight of a beam from the laser diode 30 received by a detector 32provided for the enclosure 12 is inputted as an ID signal and an MOsignal to the read LSI circuit 28 via a head amplifier 34. The read LSIcircuit 28 has circuit functions of an AGC circuit, a filter, a sectormark detecting circuit, a synthesizer, a PLL, and the like. The read LSIcircuit 28 forms a read clock and read data from the inputted ID signaland MO signal and outputs them to the decoder 26. Since the zone CAV isused as a recording method of the medium by a spindle motor 40, aswitching control of a clock frequency corresponding to a zone isexecuted for the synthesizer built in the read LSI circuit 28 by the MPU14. The modulation of the encoder 22 and the demodulation of the decoder26 are switched to the modulation and demodulation of the PPM recordingin case of the media of 128 MB and 230 MB in accordance with the mediumkind recognized by the optical disk controller 18. They are switched tothe modulation and demodulation of the PWM recording in case of themedia of 540 MB and 640 MB. A detection signal of a temperature sensor36 provided on the enclosure 12 side is supplied to the MPU 14. On thebasis of an environment temperature in the apparatus detected by thetemperature sensor 36, the MPU 14 controls each of the light emittingpowers for reading, writing, and erasing in the laser diode controlcircuit 24 to an optimum value. As a control for optimizing the lightemitting powers, in the invention, there is executed a test writing suchthat when an upper write command is received with respect to the 540-MBand 640-MB media, a test pattern is written into a test region of themedium and, after that, the test pattern is read out, and the optimumlight emitting power is found while discriminating the number of errors.According to the invention, there is executed a division test writingsuch that a test writing is divided every group of steps, when the upperwrite command is received, diving processes are sequentially executed,when an executing time exceeds a predetermined time, the dividingprocesses are interrupted, and when the upper write command issubsequently received, the dividing process of the test writing isexecuted from the interrupted step. Further, the MPU 14 controls thespindle motor 40 provided on the enclosure 12 side by a driver 38. Sincethe recording format of the MO cartridge is the ZCAV, the spindle motor40 is rotated at a constant speed of, for example, 3600 rpm. The MPU 14also controls an electromagnet 44 provided on the enclosure 12 side viaa driver 42. The electromagnet 44 is arranged on the side opposite tothe beam irradiating side of the MO cartridge loaded in the apparatusand supplies an external magnetic field to the medium in the recordingand erasing modes. A DSP 15 realizes a servo function for positioningthe beam from the laser diode 30 to the medium. For this purpose, a4-split detector 46 for receiving a beam mode light from the medium isprovided for the optical unit on the enclosure 12 side, and an FESdetecting circuit (focusing error signal detecting circuit) 48 forms afocusing error signal E1 from photosensing outputs of the 4-splitdetector 46 and inputs it to the DSP 15. A TES detecting circuit(tracking error signal detecting circuit) 50 forms a tracking errorsignal E2 from the photosensing outputs of the 4-split detector 46 andinputs it to the DSP 15. The tracking error signal E2 is inputted to aTZC circuit (track zero-cross point detecting circuit) 45 and a trackzero-cross pulse E3 is formed and inputted to the DSP 15. Further, alens position sensor 52 for detecting a position of an objective lensfor irradiating the laser beam to the medium is provided on theenclosure 12 side and a lens position detection signal (LPOS) E4 of thelens position sensor 52 is inputted to the DSP 15. The DSP 15 drives afocusing actuator 56, a lens actuator 60, and a VCM 64 via drivers 54,58, and 62 for the purpose of beam positioning.

FIG. 2 schematically shows the enclosure in the optical disk drive. Thespindle motor 40 is provided in a housing 66. By inserting an MOcartridge 70 from the side of an inlet door 68 to a hub of a rotaryshaft of the spindle motor 40, a loading such that an MO medium 72 inthe MO cartridge 70 is attached to the hub of the rotary shaft of thespindle motor 40 is performed. A carriage 76 which can be moved in thedirection traversing the medium tracks by the VCM 64 is provided belowthe MO medium 72 of the MO cartridge 70 loaded. An objective lens 80 ismounted on the carriage 76 and a beam from a semiconductor laserprovided for a fixed optical system 78 enters the objective lens 80 viaa prism 82, thereby forming a beam spot onto the surface of the MOmedium 72. The objective lens 80 is moved in the optical axial directionby the focusing actuator 56 shown in the enclosure 12 in FIG. 1 and canbe also moved in a radial direction traversing the medium tracks withina range of, for example, tens of tracks by the lens actuator 60. Theposition of the objective lens 80 mounted on the carriage 76 is detectedby the lens position sensor 52 in FIG. 1. The lens position sensor 52sets the lens position detection signal to “0” at a neutral positionwhere the optical axis of the objective lens 80 is directed rightoverhead and generates the lens position detection signal E4 accordingto movement amounts having different polarities for the movement to theouter side and the movement to the inner side.

[LD light emission control]

FIG. 3 is a circuit block diagram of the laser diode control circuit 24provided for the control unit 10 in FIGS. 1A and 1B and shows an MOcartridge medium which needs the erasing operation before the writingoperation as an example. With respect to a medium of the directoverwrite corresponding type which doesn't need the erasing operation,an erasing power of the MO cartridge is replaced by an assisting powerfor increasing the rising speed of a writing power in case of the directoverwriting operation. In the laser diode unit 30, a laser diode 100 anda monitor photodiode 102 are integratedly provided. The laser diode 100receives a driving current I by a power voltage Vcc and emits light. Alaser beam is formed and irradiated to the medium surface by the opticalunit and the recording and reproducing operations are performed. Themonitor photodiode 102 receives a part of the light from the laser diode100 and outputs a photosensing current i0 which is proportional to thelight emitting power of the laser diode 100. A reading power currentsource 104, an erasing power current source 106, a first writing powercurrent source 108, and a second writing power current source 110 areconnected in parallel to the laser diode 100 and supply a reading powercurrent I0, an erasing power current I1, a first writing power currentI2, and a second writing power current I3, respectively. That is, thereading power current I0 flows at the time of the reading power lightemission, a current (I0+I1) obtained by adding the erasing power currentI1 to the reading power current I0 flows at the time of the erasingpower light emission, and a current (I0+I1+I2) obtained by furtheradding the first writing power current I2 to the current (I0+I1) flowsat the time of the first writing power light emission. A current(I0+I1+I3) obtained by adding the second writing power current I3 to thereading power current I0 and erasing power current I1 flows at the timeof the second writing power light emission. An automatic power controlunit (hereinbelow, called an “APC”) 138 is provided for the readingpower current source 104. A specified target reading power is set as atarget power into the APC 138 via a target DAC register 120 and a D/Aconverter (hereinbelow, called a “DAC”) 136. An EP current DAC register122 and a DAC 140 are provided as an EP current instructing unit for theerasing power current source 106. A WP1 current DAC register 124 and aDAC 142 are provided as a WP1 current instructing unit for the firstwriting power current source 108. Further, a WP2 current DAC register126 and a DAC 144 are provided as a WP2 current instructing unit for thesecond writing power current source 110. Consequently, the currents ofthe current sources 104, 106, 108, and 110 can be properly changed bysetting DAC instruction values to the corresponding registers 120, 122,124, and 126, respectively. A light emission current source circuit isconstructed by the registers, DACs, and constant current sources. TheAPC 138 executes a feedback control so that a monitor current imobtained from the photosensing current i0 of the photodiode 102coincides with the target voltage of the DAC 136 corresponding to thetarget reading power. For this purpose, subtraction current sources 112,114, and 116 are provided for the monitor photodiode 102 in order tosubtract the photosensing currents when the light is emitted by theerasing power and the first and second writing powers which exceed thereading power and to feed back the monitor current im corresponding tothe reading power to the APC. An arbitrary subtraction current i1 can beset to the subtraction current source 112 for the erasing power by an EPsubtraction DAC register 128 and a DAC 146 serving as an EP subtractioncurrent instructing unit. An arbitrary subtraction current i2 can be setto the subtraction current source 114 for the first writing power by aWP1 subtraction DAC register 130 and a DAC 148 serving as a WP1subtraction current instructing unit. Further, an arbitrary subtractioncurrent i3 can be also set to the subtraction current source 116 for thesecond writing power by a WP2 subtraction DAC register 132 and a DAC 150serving as a WP2 subtraction current instructing unit. The monitorcurrents im in the light emitting modes of the above three subtractioncurrent sources i1, i2, and i3 are as follows.

I. At the time of the reading power light emission:

im=i0

II. At the time of the erasing power light emission:

im=i0−i1

III. At the time of the first writing power light

emission: im=i0−(i1+i2)

IV. At the time of the second writing power light

emission: im=i0−(i1+i3)

Consequently, at the time of the light emission by any one of theerasing power, the first writing power, and the second writing powerexceeding the target reading power, by subtracting the correspondingsubtraction current from the photosensing current i0, the monitorcurrent im is supplied as a current corresponding to the reading powerto a resistor 118 for detecting a monitor voltage and is fed back to theAPC 138. The APC 138, therefore, controls the reading power currentsource 104 so as to always maintain the target reading powerirrespective of the kind of light emitting power, thereby realizing theautomatic power control of the specified erasing power, first writingpower, and second writing power. With respect to the subtraction currentas well, a subtraction current source circuit is constructed by theregisters, DACs, and constant current sources. A monitor voltage by themonitor voltage detecting resistor 118 corresponding to the monitorcurrent im is converted to digital data by an A/D converter(hereinbelow, called an “ADC”) 152. After the digital data was inputtedto a monitor ADC register 134, it is read out to the MPU 14 side. TheADC 152 and monitor ADC register 134 consequently construct a measuringunit of the monitor current im.

FIG. 3 shows the MO cartridge which requires the erasing operation as anexample. In case of a cartridge medium of the direct overwritecorresponding type which does not need the erasing operation, in the PWMrecording, a first writing power WP1 and a second writing power WP2 areadded to a power (RP+AP) obtained by adding an assisting power AP to areading power RP. In the PPM recording, the first writing power WP1 isadded to the power (RP+AP) obtained by adding the assisting power AP tothe reading power RP. Consequently, it is sufficient that the registers124 and 128, the DACS 142 and 146, and the current sources 110 and 112for an erasing power EP in FIG. 3 are replaced to those for theassisting power AP. It will be obviously understood that registers,DACs, and current sources which are exclusively used for the assistingpower can be also added.

FIGS. 4A to 4J are time charts for signals of the PWM recording, lightemission current, and subtraction current in the laser diode controlcircuit 24 in FIG. 3 and show the cartridge medium of 540 MB or 640 MBof the direct overwrite corresponding type which does not need theerasing operation as an example. Now, assuming that write data of FIG.4B was supplied synchronously with a write gate of FIG. 4A, the writedata is converted to pulse width data of FIG. 4D synchronously with awrite clock of FIG. 4C. On the basis of the pulse width data, an assistpulse as shown in FIG. 4E is generated and, further, a first write pulseas shown in FIG. 4F is generated. Further, a second write pulse of FIG.4G is generated. The second write pulse has the number of pulsesaccording to the pulse width of the pulse width data of FIG. 4D. Forexample, the head pulse width data has a pulse width of four clocks, thenext pulse width data has a pulse width of two clocks, and the followingpulse width data has a pulse width of three clocks. In correspondencewith it, the second write pulse of FIG. 4G generates two pulses withrespect to the four-clock width of the head data after the first writepulse of FIG. 4F, generates zero pulse with respect to the nexttwo-clock width, and generates one pulse with respect to the third pulsewidth of three clocks, thereby recording information indicative of thepulse width. FIG. 4H shows the light emission currents and powers basedon the assist pulse of FIG. 4E, first write pulse of FIG. 4F, and secondwrite pulse of FIG. 4G. A read current is always supplied and a DC lightemission is performed by the reading power RP. Consequently, a lightemission current (I0+I1) flows synchronously with the assist pulse, sothat the current is increased by an amount corresponding to the assistpower AP. The light emission current I2 is added at the timing of thefirst write pulse, so that the current is increased by an amountcorresponding to the first writing power WP1. Further, the lightemission current I3 is added at the timing of the second write pulse(I0+I1+I3), so that the current is increased by an amount correspondingto the second writing power WP2. Synchronously with the light emissioncurrent of FIG. 4H, a subtraction current of FIG. 4I flows in thesubtraction current sources 112, 114, and 116 in FIG. 3. That is, thesubtraction current i1 corresponding to the increased amount of theassisting power AP flows. The subtraction current i2 corresponding tothe increased amount of the next first writing power WP1 is added and aresultant subtraction current (i1+i2) flows. Further, the subtractioncurrent i3 corresponding to the increased amount of the second writingpower WP2 is added and a resultant subtraction current (i1+i3) flows.The monitor current im of FIG. 4J is a value obtained by subtracting thesubtraction current of FIG. 4H from the photosensing current i0corresponding to the light emission current and the light emitting powerof FIG. 4H and is always converted to a constant current correspondingto the reading power even during light emission and the constant currentis fed back to the APC 138.

FIGS. 5A to 5J are timing charts for signals, light emission currents,subtraction current, and monitor current when the PPM recording isperformed to the medium of 540 MB or 640 MB of the direct overwritecorresponding type as an example. Now, assuming that write data of FIG.5B was supplied synchronously with a write gate of FIG. 5A, pulse widthdata of FIG. 5D is formed synchronously with a write clock of FIG. 5C.In correspondence to the pulse width data, an assist pulse of FIG. 5Eand a first write pulse of FIG. 5F are generated. In the PPM recording,a second write pulse of FIG. 5G is not used. By supplying a lightemission current of FIG. 5H by the assist pulse and the first writepulse to the laser diode, a light emitting power P can be obtained. Inthe PPM recording, a power (PR+AP) is obtained by adding the assistingpower AP to the reading power RP at the timing of the assist pulse. Inthis case, the assisting power AP is set to the reading power RP itself(AP=RP), so that the light emission by the reading power RP by thereading power current I0 is maintained even at the timing of the assistpulse. At the timing of the first write pulse, the light emissioncurrent is increased only by an amount of (I1+I2) and a power obtainedby adding an amount of the assisting power AP to an amount of the firstwriting power WP1 is used. A subtraction current (i1+i2) of FIG. 5I issupplied at the light emission timing of the first write pulse. Themonitor current im of FIG. 5J is, therefore, always maintained to acurrent equivalent to the photosensing current of the reading power.

[Division test writing process]

FIGS. 6A and 6B are functional block diagrams of a division test writingprocess according to the invention which is realized by the MPU 14 inthe optical disk drive in FIGS. 1A and 1B. A division test writingprocessing unit 160 is constructed by a division control unit 162 and adivision executing unit 173. The division control unit 162 discriminatesabout the necessity of the test writing process when a write command isreceived from the upper apparatus. If the test writing process isnecessary, the division executing unit 173 is started and allowed toperform the test writing process. There are following two processes fordetermining about the necessity of the test writing by the divisioncontrol unit 162.

I. Determination about the necessity of the test writing based on theelapsed time since the medium has been loaded.

II. Determination about the necessity of the test writing based on achange in temperature in the apparatus detected by the temperaturesensor 36 in FIG. 1.

In order to determine the necessity of the two test writing, thedivision control unit 162 has an elapsed time control unit 164 and atemperature change control unit 166. The determination of the necessityof the test writing by the elapsed time control unit 164 and temperaturechange control unit 166 is as shown in a time schedule of FIG. 7A.

FIG. 7A shows the time schedule when the medium cartridge is loaded intothe optical disk drive. A period of time which is required until, forexample, a time of 160 seconds elapses from the loading of the medium isset to a valid time test write processing period 204 for determining thenecessity of the test writing by the elapsed time control unit 164. Withrespect to the time after 160 seconds when the valid time test writeprocessing period 204 has passed, the time schedule is switched to atemperature change test write processing period 206 by the temperaturechange control unit 166. The valid time test write processing period 204is started from the timing of the loading of the medium into the opticaldisk drive. The elapsed time from the medium loading is measured by anelapsed time timer 170 provided in the division control unit 162 inFIGS. 6A and 6B. The time measured by the elapsed time timer 170 isexpressed by an elapsed time A. When the medium is loaded in FIG. 7A, afirst write command is issued from the upper apparatus. In response tothe first write command, the elapsed time control unit 164 in thedivision control unit 162 turns on a batch execution flag for setting abatch process and a dividing process of the test writing, for thedivision executing unit 173 and a batch test writing process isexecuted. That is, in the invention, the test writing process is dividedinto a plurality of execution units which are sequentially executed eachtime the write command is received from the upper apparatus. Withrespect to the first write command, however, since the optimum lightemitting power is not obtained, the dividing process is not executed andthe optimum light emitting power is found by the batch test writing.When the batch test writing is performed by the first command in FIG. 7Aand the optimum light emitting power is determined, a valid time Tv inwhich the optimum light emitting power determined by the batch testwriting can be validly used is set in accordance with the elapsed time Ameasured by the elapsed time timer 170 at that time. The relation of thevalid time Tv to the elapsed time A is set by a valid time table 168.

FIG. 8 shows an example of the valid time table 168 in FIGS. 6A and 6B.The valid time Tv is set so as to be longer as the elapsed timeincreases. For example, when the optimum light emitting power isdetermined by the test writing within 0 to 19 seconds of the elapsedtime A, the valid time Tv is set to 20 seconds. With respect to theelapsed time of 20 to 39 seconds, the valid time Tv is set to 40seconds. With respect to the elapsed time of 40 to 59 seconds, Tv is setto 60 seconds. With respect to the elapsed time of 60 to 160 seconds, Tvis set to 160 seconds. That is, just after the power of the optical diskdrive was turned on and the medium cartridge was loaded, the temperaturein the drive rapidly increases and a distribution of the temperatures inthe drive is not even. When the elapsed time A is short, therefore, thetest writing is frequently performed. When the elapsed time A is long,the valid time Tv is set so as to reduce the frequency of the testwriting and the necessity of the test writing is determined.

FIG. 7B is a time schedule for the division test writing process when awrite command from the upper apparatus is received in the valid timetest write processing period 204 after the first optimum light emittingpower was determined by the batch test writing based on the firstcommand in FIG. 7A. At the time point of the completion of the previoustest writing process, the valid time Tv when the next test writing isnecessary is set from the valid time table of FIG. 8 on the basis of theelapsed time A at that time. The elapsed time control unit 164 in FIGS.6A and 6B sets 90% of the valid time Tv to a test writing rest period208. Even when the write command is received from the upper apparatusfor the test writing rest period 208, the optimum light emitting powerby the previous test writing process is validated and the test writingprocess is not executed. Following to the test writing rest period 208determined by 90% of the valid time, a division test write valid period210 having the duration of 10% of the valid time set in a range from 90%to 100% of the valid period Tv is set. When the write command isreceived from the upper apparatus in the division test write validperiod 210, the elapsed time control unit 164 turns off the batchexecution flag, thereby executing the test write dividing process by thedivision executing unit 173. As shown by the division executing unit 173in FIGS. 6A and 6B, the division test writing process in the divisiontest write valid period 210 is divided into five dividing processeswhich are sequentially executed by a first division executing unit 174,a second division executing unit 176, a third division executing unit178, a fourth division executing unit 180, and a fifth divisionexecuting unit 182. The first division executing unit 174 sets a defaultvalue of the light emitting power as an initial value for obtaining theoptimum light emitting power. When the light emitting power is notobtained by a default value, the default value is updated. The defaultvalue is read out from a default erasing/assisting power table 188 and adefault writing power table 190 provided for a light emitting poweradjusting unit 186 and is set. In place of the default erasing/assistingpower table 188, a default erasing power table and a default assistingpower table which are exclusively used can be also individuallyprovided. In the first division executing unit 174, the correction ofthe default value by the temperature in the apparatus stored in aregister group 184 when the default value is set is executed by readingout a temperature correction coefficient from a temperature correctioncoefficient table 192 provided for the light emitting power adjustingunit 186. As for the setting of the default value for determining thelight emitting power for the test writing by the first divisionexecuting unit 174, the test writing is executed while changing thedefault value every predetermined default unit. Specifically, the testwriting is executed while changing the light emitting power at fivestages of (default−2), (default−1), (default), (default+1), and(default+2). The second division executing unit 176 erases a test regionof the medium by the light emission of the laser diode by the erasingpower set by the first division executing unit 174. In case of thedirect overwrite corresponding type medium, the process of the seconddivision executing unit 176 is skipped. The third division executingunit 178 drives the laser diode to emit light by the writing power setby the first division executing unit 174, thereby writing apredetermined test pattern into the erased test region. The fourthdivision executing unit 180 executes a process for reading out the testpattern written by the third division executing unit 178. Further, thefifth division executing unit 182 compares a write pattern by the thirddivision executing unit 178 with a read pattern by the fourth divisionexecuting unit 180 on a bit unit basis and obtains the number of timesof dissidence for the light emitting power at that time. In the divisiontest writing processes by the first to fifth division executing units174 to 182, the processes at the five stages (−2, −1, 0, +1, +2) arerepeated for the default value of the light emitting power by the firstdivision executing unit 174 and the fifth division executing unit 182determines the optimum light emitting power from the processing result.That is, in order to find the optimum light emitting power by one testwriting process, it is necessary to repeat the division test writing ofthe default setting, erasing, writing, reading and comparing five times.Further, when the optimum light emitting power is not found even afterthe division test writing was repeated five times, the default valueitself which is initially set by the first division executing unit 174is updated to another value, the same processes are repeated, and thetest writing is repeated until the optimum light emitting power isobtained.

FIG. 9 shows a measurement result which is obtained by the test writingprocess to decide the optimum light emitting power by the divisionexecuting unit 173 in FIG. 6 and relates to the optimum light emissionadjustment of the writing power as an example. Before the test writing,the first division executing unit 174 obtains a default power DWPcorrected by the apparatus temperature at that time and first sets awriting power

WP=DWP−2

which is lower than the default power DWP by 2 units. The erasingoperation by the second division executing unit 176, the writingoperation of the test pattern by the third division executing unit 178,and the reading operation by the fourth division executing unit 180 areexecuted. Further, the number of times of dissidence between the writingpattern and the reading pattern is measured by the fifth divisionexecuting unit 182. The number (E) of times of dissidence in this caseis equal to an 0 point and exceeds a threshold value Eth showing thelimit of the optimum light emitting power. Subsequently, a writing power

WP=DWP−1

in which the default power DWP is increased by −1 unit is updated andset into the first division executing unit 174. The erasing operation bythe second division executing unit 176, the writing operation of thetest pattern by the third division executing unit 178, and the readingoperation by the fourth division executing unit 180 are executed. Thenumber of times of dissidence of the bits between the write pattern andthe read pattern is measured by the fifth division executing unit 182.In this case, the number of times of dissidence is smaller than thethreshold value Eth indicating the limit of the optimum light emittingpower like a P point and the writing power (DWP−1) can be labeled as anoptimum power. Similarly, the writing power WP is changed to 0, +1, and+2 for the default power DWP and the number of times of dissidence atthis time is obtained as shown at Q point, R point, and S point. In thiscase, the number of times of dissidence at each of the Q point and Rpoint is smaller than the threshold value Eth and lies within the rangeof the optimum light emitting power. At the point S, the number of timesof dissidence is larger than the threshold value Eth and is out of therange of the optimum light emitting power. When the numbers of times ofdissidence in the test writing by the adjustment of the writing power WPat five stages of (−2, −1, 0, +1, +2) for the default power DWP areobtained, the median of the three points of P, Q, and R which aresmaller than the threshold value Eth, namely, the writing power WP=DWPat the point Q is determined as an optimum light emitting power. Thecharacteristics of the number of times of dissidence by the test writingfor the writing power WP are shifted to the right and left in dependenceon the temperature in the apparatus. That is, now assuming that theapparatus temperature is equal to 25° C., characteristics 212 which areshown by a solid line and are given at five measurement points of O, P,Q, R, and S by the test writing are shifted in such a direction as toincrease the optimum writing power as shown by characteristics 214 of abroken line when the apparatus temperature decreases to 10° C. On thecontrary, when the apparatus temperature increases to 55° C., thecharacteristics 212 are shifted in such a direction as to reduce theoptimum light emitting power as shown by characteristics 216 of analternate long and two short dashes line. As clearly shown from thecharacteristics 212, 214, 216 of the number of errors for the optimumlight emitting power which differs depending on the apparatustemperature, it will be understood that the optimum light emitting powerat the time of the test writing largely fluctuates due to the apparatustemperature at that time. Therefore, when the test writing is executedin a state where the optimum writing power corresponding to theapparatus temperature at that time is far from the default writingpower, for example, in a state like the characteristics 216 when theapparatus temperature rises to 55° C., there is a case where the optimumwriting power cannot be found in the test writing at five stages by (−2,−1, 0, +1, +2) of the writing power for the default power DWP.Therefore, it is necessary to correct the default power DWP toDWP=DWP−1, change the writing power WP to (−2, −1, 0, +1, +2) for thedefault power after the correction, and execute the test writing.Therefore, it will be understood that if the apparatus temperaturelargely changes and the optimum power is largely deviated from thedefault, it takes a fairly long time to search the optimum writingpower. Thus, a fairly long time is required until the optimum lightemitting power is found and the apparatus determines that the time-outoccurred for the access from the upper apparatus, resulting in an error.According to the invention, however, as shown in the division executingunit 173 in FIGS. 6A and 6B, the test writing of one time until theerasing, writing, reading, and comparison deciding operations after thelight emitting power was set is divided into five processes and isexecuted. Until the optimum default power is found after completion ofthe dividing process, the apparatus responds to an upper command by theaccess by the previous optimum light emitting power. Therefore, even ifit takes a long time for the test writing to find the optimum lightemitting power, a situation such that the apparatus determines theoccurrence of the time-out for the upper command and the error occurscan be certainly prevented.

In the temperature change control unit 166 provided for the divisioncontrol unit 162 in FIGS. 6A and 6B, as shown in the time schedule fromthe medium loading in FIG. 7A, the necessity of the test writing isdiscriminated with respect to the temperature change test writeprocessing period 206 set as a period of time after the elapse of thevalid time test write processing period 204 for 160 seconds. That is,the temperature change control unit 166 detects the apparatustemperature every maximum time, namely, Tv=160 seconds of the valid timeTv set by, for example, the final time of 160 seconds in the valid timetest write processing period 204 in the temperature change test writeprocessing period 206 and calculates a temperature difference betweenthe detected temperature and the previous detection temperature. Whenthe temperature difference is equal to or higher than, for example, 3°C., it is determined that the test writing is necessary. Each time thewrite command is received from the upper apparatus, as shown in FIG. 7A,the dividing processes of the first to fifth division executing units174 to 182 provided for the division executing unit 173 are sequentiallyrepeated. On the other hand, the division test writing process has anadvantage such that it is possible to prevent the situation such thatwhen it takes a time to decide the optimum light emitting power, thetime-over occurs for the upper command and an error occurs. However, ifthe interruption period of time of the dividing process is contrarily solong, the apparatus temperature largely changes for such a longinterruption period of time and there is a case where the results up tothe previous dividing process cannot validly be used. In the elapsedtime control unit 164, therefore, as shown in FIG. 7B, with respect tothe period of time after the elapse of the division test write validperiod 210 having a width of the valid time of 10% of the range from 90%to 100% of the valid time Tv, namely, after the elapse of the valid timeTv, a batch test writing period 211 is set. When the process isinterrupted during the dividing process without finishing all of thedivision test writing processes until the valid time Tv, if the writecommand is received from the upper apparatus at the time point of theelapse of the valid time Tv, the processing mode is switched to thebatch test writing mode for performing the remaining dividing processesin a lump. Thus, inconvenience such that the division test writing isexecuted over the valid time Tv and the time required for the testwriting which was divisionally executed is too long and the optimumlight emitting power is deviated during such a long time is prevented.

In the temperature change control unit 166 in FIGS. 6A and 6B, if thetemperature difference by the detection of the apparatus temperature ofevery maximum valid time Tv=160 seconds is equal to or larger than, forexample, 4° C. exceeding 3° C. which is used to discriminate about thenecessity of the division test writing process, it takes a time and theadjustment of the optimum light emitting power is delayed in case ofperforming the division test writing process. In this case, therefore,the processing mode is switched to the batch test writing process toexecute the remaining division test writing processes in a lump. Eachtime the dividing process is executed, the temperature differencebetween the present temperature and the detection temperature in theprevious dividing process is checked. For instance, when there is atemperature change of 2° C. or more, since the results of the dividingprocesses so far cannot validly be used, in this case, all of thedividing processes so far are cancelled and the dividing processes areagain executed from the beginning.

In addition to the apparatus temperature, the medium kind, write/eraseinformation indicative of the kind of upper command, and the zone numberof the medium in which the access track is included have been set in theregister group 184 to execute the dividing process in the division testwrite processing unit 160 in FIGS. 6A and 6B. As a kind of medium whichis set into the register group 184, there are media of 128 MB, 230 MB,540 MB, and 640 MB. Further, information indicating whether the mediumis an overwrite medium in which data can be written without needing theerasing operation or an ordinary medium in which the erasing and writingoperations are individually executed is also stored. When the medium isthe overwrite medium, since the erasing operation is unnecessary, theprocess by the second division executing unit 176 provided for thedivision executing unit 173 is not performed. As for the zone number ofthe register group 184, the medium zone in case of the media of 540 MBand 640 MB is divided into three areas and the optimum light emittingpower by the test writing is found in the test writing process in thedivision test write processing unit 160. Therefore, the medium areawhere the test writing is executed is discriminated by the zone number.The test writing operations in the division test write processing unit160 are executed in parallel every area. The medium area for the testwriting in the media of 540 MB and 640 MB is divided into three areas ofan inner rim area, an intermediate area, and an outer rim area. Forexample, in case of the 640-MB medium, there are 11 zones and they areclassified in a manner such that the zone numbers 1 to 4 correspond tothe inner rim area, the zone numbers 5 to 8 correspond to theintermediate area, and the zone numbers 9 to 11 correspond to the outerrim area. An inherent optimum light emitting power is found for eacharea by the test writing. Since there are 18 zones in case of the 540MBmedium, they are divided into three areas of an inner rim area, anintermediate area, and an outer rim area on a 6-zone unit basis. Anoptimum light emitting power is found every area by the test writing.

The light emitting power adjusting unit 186 in FIGS. 6A and 6B will nowbe described. The light emitting power adjusting unit 186 executes alight emitting power adjusting process upon activation in associationwith the power-on of the optical disk drive and stores a processingresult into the default erasing assisting power table 188 and defaultwriting power table 190 as default values. Further, the temperaturecorrection coefficient table 192 in which temperature correctioncoefficients corresponding to the apparatus temperature have been storedis provided. For example, in case of the 640-MB medium, default erasingpowers DEPi have been stored as, for example, 3.0 mW to 4.5 mW in thedefault erasing/assisting power table 188 in correspondence to the zonenumbers 1 to 11 as shown in FIG. 10. As shown in FIG. 11, for example,in case of the 640-MB medium, default writing powers DWP=6.0 mW to 11.0mW have been stored in the default writing power table 190 incorrespondence to the zone numbers i=1 to 11. Further, as shown in FIG.12, temperature correction coefficients Kt=−0.10 to 0.10 have beenstored in the temperature correction coefficient table 192 incorrespondence to the zone numbers i=1 to 11 of the 540-MB medium. Thecoefficients Kt in the temperature correction coefficient table 192 inFIG. 12 show the values in case of the apparatus temperature T=25° C.Referring again to FIGS. 6A and 6B, an erasing/assisting power table194, a first writing power table 196, and a second writing power table198 to store the optimum light emitting power found out by the testwriting of the division test write processing unit 160 are furtherprovided for the light emitting power adjusting unit 186. The erasingpower EP which is used for the ordinary MO cartridge and the assistingpower AP which is used for the direct overwrite medium have been storedin the erasing/assisting power table 194 and are selectively used inaccordance with the discrimination result of the medium kind. In placeof the erasing/assisting power table 194, the exclusive-use erasingpower table and assisting power table can be also individually provided.Two kinds of writing powers which are used for the PWM recording shownin the time charts of FIGS. 4A to 4J have been stored in the firstwriting power table 196 and second writing power table 198. Defaultvalues in the first writing power table 196 have been stored in thedefault writing power table 190 and a power ratio of the second writingpower to the first writing power has been predetermined. Therefore, bymultiplying the default writing power in the default writing power table190 by a predetermined power ratio, the second writing power WP2 isobtained and the second writing power table 198 can be obtained. Asinitial values of the erasing/assisting power table 194, first writingpower table 196, and second writing power table 198, the temperaturecorrection coefficients Kt are obtained with reference to thetemperature correction coefficient table 192 based on the apparatustemperature in a register 200 at that time, and the values obtained bytemperature correcting the default values in the defaulterasing/assisting power table 188 and default writing power table 190 bythe temperature correction coefficients Kt are stored. An equation forthe temperature correction is given by

WP=DWP(1+Kt)

where,

WP: writing power after completion of the temperature correction

DWP: default writing power

Kt: temperature correction coefficients corresponding to the zone No. i

The processing operation by the division test write processing unit 160in FIGS. 6A and 6B will now be described. FIG. 13 is a schematic diagramof the whole processes in the optical disk drive having the divisiontest write processing unit 160 in FIGS. 6A and 6B according to theinvention. When the power supply of the optical disk drive is turned on,an initializing process is executed in step S1. A setting adjustment ofeach default value, temperature correction coefficients, and the like bythe light emitting power adjusting unit 186 in FIGS. 6A and 6B isincluded in the initializing process. When the medium loading isdiscriminated in step S2, step S3 follows and the measurement of theelapsed time (A) by the elapsed time timer 170 is started. In step S4,whether the command has been received or not is discriminated. When thecommand is received from the upper apparatus, a check is made in step S5to see if the received command is the write command. If YES, step S6follows and a check is made to see if the elapsed time (A) measured bythe elapsed time timer 170 is shorter than 160 seconds. When it isshorter than 160 seconds, step S7 follows and the test writing processbased on the valid time by the elapsed time control unit 164 isexecuted. When the test writing process is finished, the write commandfrom the upper apparatus is executed in step S8. In step S9, when themedium is not unloaded, the processing routine is returned to step S4and the apparatus waits for the reception of a next command from theupper apparatus. In step S6, when the elapsed time (A) is equal to orlonger than 160 seconds, step S11 follows and the test writing processbased on the temperature change by the temperature change control unit166 in FIGS. 6A and 6B is executed. After completion of the test writingprocess, the write command from the upper apparatus is executed in stepS8. When the read command is discriminated in step S5, the read commandis executed in step S8. When the medium unloading is discriminated instep S9, step S10 follows. When the apparatus is not stopped, theprocessing routine is returned to step S2 and the apparatus waits forthe loading of a next medium. When the apparatus is stopped, a series ofprocesses are finished.

FIG. 14 is a flowchart for the valid time test writing process which isexecuted in the valid time test write processing period 204 in FIG. 7Awhen the elapsed time (A) from the medium loading is shorter than 160seconds in step S7 in FIG. 13. In the valid time test writing process, acheck is made to see if the write command from the upper apparatus isthe first command in step S1. In case of the first write command, stepS2 follows. In this case, since the optimum light emitting power is notfound, the batch execution flag is turned on and the dividing processesof the division test writing process are not executed in step S9. Theprocesses by the five first to fifth division executing units 174 to 182provided for the division executing unit 173 in FIGS. 6A and 6B areexecuted in a lump, thereby finding the optimum light emitting power.When the batch test writing by the turn-on of the batch execution flagis finished, the valid time Tv is obtained from the elapsed time (A) atthat time in step S11 and a valid time timer 172 is started. Ameasurement time of the valid time timer 172 is labeled as (B). When thecommand is the second or subsequent write command from the upperapparatus in step S1, the measurement time (B) of the valid time timer172 is read in step S3. In step S4, a check is made to see whether thevalue (B) of the valid time timer 172 is equal to or longer than the 90%valid time of the valid time Tv at that time or not. When the value (B)is smaller than the 90% valid time, the processes in steps S5 to S11 areskipped and the division test writing is not performed. When the value(B) of the valid time timer is equal to or larger than the 90% validtime in step S4, step S5 follows. A check is made to see whether thevalid time timer value (B) is equal to or larger than the valid time Tvat that time or not. When the value (B) is smaller than the valid timeTv, the batch execution flag is turned off in step S6. The division testwriting process is executed in step S9. In this case, a check is made instep S7 to see whether the elapsed time from the previous execution ofthe dividing process is equal to or larger than the 10% valid time ofthe valid time Tv at that time or not. If the elapsed time of thedividing process exceeds the 10% valid time, the results of the dividingprocesses so far cannot be validly used. Therefore, the divisionprocessing number is cleared in step S8, thereby again executing thedivision test writing process in step S9 from the beginning. In thedivision test writing process in step S9, with reference to the divisionprocessing numbers #1, #2, #3, #4, and #5 which have previously beenrespectively allocated to the first to fifth division executing units174 to 182 of the division executing unit 173 in FIGS. 6A and 6B, theprocess of the division executing unit corresponding to the headdivision processing number which is not yet processed at that time isexecuted. When any one of the division test writing processes isfinished in step S9, a check is made in step S10 to see if the divisiontest writing process has been completed. If NO, the processing routineis again returned to the main routine in FIG. 13 and the apparatus waitsfor the division test writing by the next upper command. When thedivision test writing process is completed, the valid time Tv isobtained from the elapsed time (A) measured by the elapsed time timer170 with reference to the valid time table 168 in FIG. 8. The valid timetimer 172 for monitoring the next valid time is cleared and started.

The division test writing process in step S9 in FIG. 14 is as shown inflowcharts of FIGS. 15A, 15B, 16A, and 16B. The division test writingprocess in FIGS. 15A to 16B is divided into five processing portionsshown by the first to fifth division executing units 174 to 182 like adivision executing unit 173 in FIGS. 6A and 6B and the processingnumbers #1 to #5 are set, respectively. That is, steps S1 to S10 relateto a process of the processing No. #1 by the first division executingunit 174. Steps S11 to S16 relate to the process of the processing No.#2 by the second division executing unit 176. Steps S17 to S21 relate tothe process of the processing No. #3 by the third division executingunit 178. Steps S22 to S26 relate to the dividing process of theprocessing No. #4 by the fourth division executing unit 180. Steps S27to S34 relate to the dividing process of the processing No. #5 by thefifth division executing unit 182.

First, a default setting updating process by the first divisionexecuting unit 174 in steps S1 to S10 corresponding to the processingNo. #1 will be explained. First in step S1, a check is made to see if alaser diode readjustment flag is ON. The laser diode readjustment flagis turned on by an error recovering process, for example, when a readerror or a write error occurs by the execution of the upper command. Instep S2, the readjustment of the laser diode by the light emitting poweradjusting unit 186 in FIGS. 6A and 6B is executed. Generally, since thelaser diode readjustment flag is OFF, the readjustment of the laserdiode in step S2 is skipped. In step S3, subsequently, a medium area ofthe access track designated by the write command from the upperapparatus is discriminated. In case of the medium of 540 MB or 640 MBwhich needs the test writing, the medium zone is divided into threeareas of the inner rim area, intermediate area, and outer rim area.Therefore, the medium area for test writing which belongs to the accesstrack is discriminated from the zone number. In step S4, a seekingoperation to position the light beam to the test area of the medium areadiscriminated is executed. In case of dividing the medium into threeareas of the inner rim area, intermediate area, and outer rim area, forexample, in case of the 640-MB medium, as shown in the default erasingpower table in FIG. 10, the inner rim area corresponds to the zone Nos.1 to 4, the intermediate area corresponds to the zone Nos. 5 to 8, andthe outer rim area corresponds to the zone Nos. 9 to 11. In the zoneNos. 1 to 11, for example, five tracks at the zone boundary of each zoneare preliminarily allocated as one user area. The non-user area at thezone boundary can be used as a test area for the test writing. In thiscase, each area is divided into a plurality of zones and is distributedto 5 track portions at each zone boundary of the non-user area.Therefore, it is desirable to execute the test writing while using thenon-user area of the zone locating at the center of each area as a testarea. In step S5, the present time is preserved and a check is made tosee if the next dividing process has been executed. In the initialstate, since all of the processes of the division processing numbers #1to #5 are not yet executed, the light emitting power for test writing isinitially set on the basis of the apparatus temperature at that time inaccordance with the head division processing No. #1 which is not yetexecuted. The initial setting of the light emitting power is executed bythe light emitting power adjusting unit 186 in FIGS. 6A and 6B. Thedefault values and the temperature coefficients are read out from thedefault erasing/assisting power table 188, default writing power table190, and temperature correction coefficient table 192. The defaulterasing power DEP, default first writing power DWP1, and default secondwriting power DWP2 which were respectively corrected by the temperaturecoefficients are obtained. A power in which the initial value “−2” amongthe values in which the light emitting power is set to five stages of(−2, −1, 0, +1, +2) from each default value is subtracted from thedefault power is initially set. In case of the overwrite medium, anassisting power AP obtained by subtracting the initial value “−2” fromthe default assisting power DAP is initially set. Subsequently, in stepS8, the division processing No. #1 showing the end of the settingprocess by the first division executing unit 174 is preserved. In stepS9, a check is made to see if the batch execution flag is ON. In thiscase, since the batch execution flag is OFF, step S10 follows and acheck is made to see if the processing time exceeded a predetermineddivision executing time of 0.5 second. When exceeding 0.5 second at thistime, the processes after step S11 are not executed but the processingroutine is returned to the main routine in FIG. 13. On the other hand,when it doesn't exceed 0.5 second in step S10, step S11 follows and acheck is made to see if the next dividing process has been executed.

Since the process of the division processing No. #2 of the seconddivision executing unit 176 as a next dividing process is not yetexecuted, step S12 follows and a check is made to see if the medium isthe overwrite medium. In case of the overwrite medium, since the erasingoperation of the test sector in step S13 is unnecessary, this process isskipped. In case of the ordinary MO medium, the test sector is erased instep S13 by the light emission of the erasing power EP=DEP1−2 at thattime. When the erasing operation of the test sector in step S13 isfinished, the division processing No. #2 is preserved in the RAM or thelike in step S14. In step S15, a check is made to see if the batchexecution flag is ON. In step S16, a check is made to see if theprocessing time has exceeded 0.5 second. If YES, the processes afterstep S17 are not executed and the processing routine is returned to themain routine in FIG. 13. When the time is equal to or shorter than 0.5second in step S16, step S17 in FIG. 16 follows. A check is made to seeif the next dividing process has been executed, namely, whether theprocess of the division processing No. #3 of the third divisionexecuting unit 178 has been executed. When the process of the divisionprocessing No. #3 is not executed yet, the writing process of the testpattern for the test writing sector is executed in step S18. In thewriting process of the test writing sector in this case, the ECC and CRCare not formed and only the writing operation of predetermined writepatterns is executed. As test patterns which are used for the writingprocess, test patterns prepared in the RAM at the time of the batch testwriting process by the first write command are used. As write patternswhich are prepared in the RAM, “596595” as a worst pattern in which itis predicted that an error generation probability is the largest and“FEDC . . . 3210” as all patterns of each word of hexadecimal notationare used. After completion of the writing process for the test writingsector in step S18, the division processing No. #3 of the writingprocess is preserved in the RAM in step S19. After that, a check is madein step S20 to see if the batch execution flag is ON. A check is made instep S21 to see if the processing time has exceeded 0.5 second. If YES,the processing routine is returned to the main routine in FIG. 13. Whenit is equal to or shorter than 0.5 second, a check is made in step S22to see if the next process of the division processing No. #3 by thethird division executing unit 178 has been executed. If it is not yetexecuted, step S23 follows and the test writing sector which was writtenin step S18 is read. As a reading process in this case, the readingprocess without an error correction of the ECC and CRC is performed.When the reading process is finished, the division processing No. #4 ispreserved in the RAM in step S24. After that, whether the batchexecution flag is ON or not is discriminated in step S25. A check ismade in step S26 to see if the processing time has exceeded 0.5 second.If YES, the processing routine is returned to the main routine in FIG.13. When the processing time doesn't exceed 0.5 second, a check is madein step S27 to see if the process of the division processing No. #5 ofthe fifth division executing unit 182 serving as a next dividing processhas been executed. When it is not yet executed, the number of errors iscalculated in step S28 from the processing results derived by thedividing processes of the division processing Nos. #1 to #4 so far. Thatis, the write patterns written in the test writing sector of the mediumin step S18 and the read pattern read out from the test writing sectorin step S23 are compared on a bit unit basis, thereby calculating thenumber of times of dissidence. In step S25, the division processing No.#5 is preserved in the RAM. After that, a check is made in step S30 tosee if the adjustment value of the light emitting power of the testwriting has exceeded “default+2” serving as a maximum adjustment value,namely, the erasing, writing, and reading processes by the setting ofthe light emitting power of five times have been finished. When they arenot yet finished, the light emitting power is increased by one unit instep S31. After that, the processing routine is again returned to stepS10 in FIG. 15B. When the processes of five times in which the lightemitting power is changed are finished, the process to calculate theoptimum power is executed in step S32. When the optimum power can becalculated, all of the division processing Nos. #1 to #5 of theprocesses which were executed are cleared. Since the new optimum powercan be set in step S34, the valid time Tv is further obtained from themeasurement time (A) of the elapsed time timer 170 at that time withreference to the valid time table 168 in FIG. 8, the valid time timer172 is cleared, and the counting operation of the valid time (B) isrestarted. When the elapsed time (A) of the elapsed time timer 170 isequal to or longer than A=160 seconds, the valid time Tv is fixed to themaximum value of Tv=160 seconds.

FIG. 17 shows the calculating process of the optimum power in step S2 inFIG. 16A. Five points of O, P, Q, R, and S showing the number of timesof dissidence when the default power DWP which gives, for example, thecharacteristics 212 in FIG. 10 is changed to (−2, −1, 0, +1, +2) areobtained by the detection result of the number of times of dissidencebased on the erasing, writing, and reading processes for five times inwhich the light emitting power is changed in FIGS. 15A to 16B.Therefore, the number of errors and the threshold value Eth todiscriminate the optimum light emitting power are compared in step S1,thereby extracting the light emitting powers having the number of timesof dissidence that is equal to or less than the threshold value Eth. Instep S2, a check is made to see if there are two or more light emittingpowers which give the number of times of dissidence that is equal to orless than the threshold value Eth. When there are two or more lightemitting powers, the optimum power is determined as ½ of the differencebetween the maximum and minimum values of the two powers in step S3.When the number of light emitting powers in which the number of times ofdissidence is equal to or less than the threshold value Eth is less than2 in step S2, namely, when there is only one light emitting power, theoptimum power cannot be determined. Therefore, step S4 follows, a powershifting direction is discriminated, and the default is corrected. Thepower shifting direction of the default in this case is corrected so asto shift the default power by one unit to the light emitting power sidein which the number of errors exceeds the threshold value Eth. In stepS5, a check is made to see if the corrected default value has exceeded apredetermined limit, namely, the lower limit value or upper limit valueof the writing power. If NO, the processing routine is returned to theroutine in FIGS. 16A and 16B. If the default power after the adjustmentexceeds the limit, the processing routine is finished as abnormality.

Flowcharts of FIGS. 18A and 18B show the batch test writing processwhich is executed when the first write command is received and they areshown as a series of flow excluding the portions which are skipped inFIGS. 15A, 15B, 16A, and 16B in a state where the batch execution flagis ON. That is, when the processes in the case where the ON state of thebatch execution flag in steps S9, S15, and S25 in FIGS. 15A to 16B isdiscriminated are extracted, only the processes in steps S1 to S4, S7,S12, S13, S18, S23, S28, S30, S32, and S34 in FIGS. 18A and 18B areexecuted. The contents of the batch test writing process are similar tothose in the corresponding steps in FIGS. 15A to 16B except for adifferent point that in the area discriminating process of the accesstrack in step S3, since the command is the first write command, thewrite data patterns which are used for test writing are prepared in theRAM.

FIG. 19 is a flowchart for the test writing process which is based onthe temperature change and is shown in step S11 in FIG. 13. As shown inthe time schedule of FIG. 7A, the test writing process based on thetemperature change is executed for the temperature change test writeprocessing period 206 after the elapse of 160 seconds corresponding tothe valid time test write processing time 204 from the medium loading.When the temperature change test writing process is activated on thebasis of the write command from the upper apparatus, a check is made instep S1 to see if the apparatus is on the way of the division testwriting. That is, whether the division test writing has been interruptedor not is discriminated. When the apparatus is not on the way of thedivision test writing, step S2 follows and the elapsed time from theprevious detection temperature is detected. The elapsed time is obtainedby the measurement time (B) of the valid time timer 172. In step S3,whether the elapsed time (B) is equal to or longer than 160 seconds ornot is discriminated. When the elapsed time (B) is shorter than 160seconds, the processes after step S4 are skipped and the processingroutine is returned to the main routine in FIG. 13. When the elapsedtime (B) is equal to or longer than 160 seconds, step S4 follows and atemperature difference between the previous and present temperatures iscalculated. In step S5, whether the temperature difference is equal toor higher than 3° C. or not is discriminated. When the temperaturedifference is equal to or higher than 3° C., step S6 follows and a checkis made to see whether it is equal to or higher than 4° C. or not. Whenit is less than 4° C., the batch execution flag is turned off in stepS7. The processing routine advances to the division test writing processin step S8. The division test writing processes in FIGS. 15A to 16B areexecuted. When the completion of the test writing is detected in stepS9, the new optimum light emitting power is obtained. Therefore, stepS10 follows and the elapsed time timer 170 is reset. After that, thevalid time timer 172 to measure the elapsed time (B) is reset andstarted. When it is determined in step SI that the apparatus is on theway of the division test writing, namely, the division test writing hasbeen interrupted, step 511 follows and a temperature difference betweenthe previous and present temperatures with respect to the divisionexecution is calculated. When the temperature change in the interruptingtime of the division execution is equal to or higher than 2° C. in stepS12, this means that since the temperature change in the divisioninterruption period of time is too large, the results obtained by thedivision execution so far cannot be validly used. Therefore, thedivision processing number is cleared in step S13, so that the divisiontest writing process is again executed from the beginning in step S8.When the temperature difference between the previous and presenttemperatures is equal to or higher than 4° C., namely, when thetemperature largely changes in step S6, since there is a possibilitythat the optimum light emitting power is largely deviated, theprocessing routine advances to step S14 and the batch execution flag isturned on. The remaining dividing processes are executed in a lump instep S8. The division test writing process in case of turning on thebatch execution flag in step S14 becomes the batch test writing processbased on the batch execution flag in FIGS. 18A and 18B.

According to the invention as mentioned above, a series of test writingprocesses accompanied with the erasing, writing, and reading operationswhen the upper command is received are divided into a plurality ofprocessing stages and are sequentially executed. Even in the case wherethe apparatus temperature suddenly changes and the optimum power islargely deviated from the default power which was initially set, so thatit takes a long time until the end of the test writing process to findthe optimum power, the processes are distributed and executed.Consequently, the access in response to the upper command is finishedduring the interruption of the dividing process of the writing power, sothat the error due to the time-out for the upper command is notgenerated. Even if the power is deviated from the optimum power duringthe dividing process of the test writing, the recording and reproductioncan be executed as much as possible. Thus, the apparatus performance canbe improved as a whole.

The above embodiment has been described with respect to the example inthe case where each time the write command from the upper apparatus isreceived, the necessity of the test writing is discriminated and thedivision test writing process is executed. As another embodiment of theinvention, however, it is also possible to construct in a manner suchthat the valid time Tv is obtained with reference to the valid timetable 168 based on the elapsed time (A) by the elapsed time timer 170from the medium loading in FIG. 7A without depending on the writecommand and, each time the valid time Tv elapses, the division testwriting is divisionally executed for the processing time of every 0.5second.

With respect to the division test writing process based on thetemperature change of the apparatus as well, it is also possible toconstruct in a manner such that when the apparatus temperature changesby, for example, 3° C. or more, the division test writing process isstarted and is divisionally executed at every processing period of timeof 0.5 second.

With respect to the valid time test write processing period, the validtime corresponding to the elapsed time in the valid time test writingprocess, and the numerical values of the temperature change in case ofdiscriminating about the necessity of the test writing on the basis ofthe temperature change which are shown in the above embodiment, propervalues can be determined as necessary and the invention is not limitedby the numerical values of the embodiment.

Although the above embodiment has been described with respect to the540-MB medium and 640-MB medium as an example, the division test writingcan be also similarly applied to the 230-MB medium. In case of the230-MB medium, however, as a medium area where the test writing isexecuted, it is sufficient to set one area with regard to the wholesurface of the medium. It is, therefore, unnecessary to divide themedium area into a plurality of areas and to execute the test writingevery area like a 540-MB medium or 640-MB medium.

Further, in the test writing of the invention, the changes of thewriting power at five stages are formed by adding and subtracting onedefault unit to/from the default value. However, the changes of thewriting power can be also formed by multiplying the default value bypredetermined coefficients such as 0.8, 0.9, 1.0, 1.1, and 1.2,respectively.

Moreover, although the invention has been described with respect to theMO cartridge medium which needs the erasing operation and the cartridgemedium of the direct overwrite corresponding type which doesn't need theerasing operation as examples, the embodiment of the invention can bealso similarly applied to other media such as optical disk of the phasechange type and disk of the recording system like a DVD-RAM or the likeusing a light power.

What is claimed is:
 1. An optical storage apparatus comprising: a light emitting power adjusting unit for adjusting a light emitting power of a laser diode which is used for recording and reproduction of a medium; and a divisional test write processing unit for dividing a test writing process into a plurality of test processes, said test processes being used to determine an optimum light emitting power by executing a test writing on said medium and performing said plurality of test processes in a range from a start of the test writing to an end thereof and for sequentially executing said test processes each time test writing start conditions according to a predetermined time schedule of elapsed times are satisfied.
 2. An optical storage apparatus comprising: a light emitting power adjusting unit for adjusting a light emitting power of a laser diode which is used for recording and reproduction of a medium; and a division test write processing unit for dividing a test writing process into a plurality of test processes, said test processes being used to determine an optimum light emitting power by executing a test writing on said medium and performing said plurality of test processes in a range from a start of the test writing to an end thereof and for sequentially executing said test processes when there is a temperature change of a predetermined value or more and when at least one predetermined time test writing start condition is satisfied.
 3. An optical storage apparatus comprising: a light emitting power adjusting unit for adjusting a light emitting power of a laser diode which is used for recording and reproduction of a medium; and a divisional test write processing unit for dividing a test writing process to determine an optimum light emitting power by executing a test writing on said medium and performing a plurality of test processes and for sequentially executing said test processes in accordance with a predetermined time schedule of elapsed times, wherein said division test write processing unit validly operates and executes said test processes for a period of time until the elapsed time from a predetermined start timing of said apparatus reaches a predetermined time.
 4. An apparatus according to claim 3, wherein said division test write processing unit determines an optimum light emitting power by executing the test processes in a lump by a first upper command, sets a valid time for making an adjustment of said optimum light emitting power unnecessary on the basis of the elapsed time until the present time, inhibits the test process for the upper command until the elapse of a time of a predetermined rate of said valid time, and allows the division to be executed for the upper command for said valid time from said predetermined rate time.
 5. An apparatus according to claim 4, wherein said division test write processing unit inhibits said test process in a time zone that is less than 90% of said valid time and permits said test process in a time zone exceeding 90% of said valid time.
 6. An apparatus according to claim 4, wherein when the elapsed time exceeds said valid time on the way of an execution stage of said test process, said division test write processing unit executes the remaining test processes in a lump by a next upper command.
 7. An apparatus according to claim 4, wherein said division test write processing unit sets the valid time so as to be long step by step in proportion to the elapsed time from said start timing.
 8. An optical storage apparatus comprising: a light emitting power adjusting unit for adjusting a light emitting power of a laser diode which is used for recording and reproduction of a medium; and a division test write processing unit for dividing a test writing process to determine an optimum light emitting power by executing a test writing on said medium and performing a plurality of test processes and for sequentially executing said test processes when there is a temperature change of a predetermined value or more, wherein said division test write processing unit validly operates and executes said test processes after the elapsed time from a predetermined start timing of said apparatus exceeds a predetermined time.
 9. An optical storage apparatus comprising: a light emitting power adjusting unit for adjusting a light emitting power of a laser diode which is used for recording and reproduction of a medium; and a division test write processing unit for dividing a test writing process to determine an optimum light emitting power by executing a test writing on said medium and performing a plurality of test processes and for sequentially executing said test processes when there is a temperature change of a predetermined value or more, wherein said division test write processing unit detects a temperature in the apparatus every predetermined time and allows said test processes to be executed when a as temperature difference between the detected temperature and a previous detection temperature exceeds a predetermined temperature.
 10. An apparatus according to claim 9, wherein when said temperature difference exceeds an upper limit temperature that is higher than said predetermined temperature during an executing stage of said test process, said division test write processing unit allows said test processes to be executed in a lump.
 11. An apparatus according to claim 10, wherein when the temperature difference between the previous and present dividing processes exceeds said predetermined temperature during the test process, said division test write processing unit cancels the processed numbers and processing results up to the previous time and again executes the test processes from the beginning.
 12. An apparatus according to claim 1, wherein said division test write processing unit validly operates and executes said test processes for a period of time until the elapsed time from a predetermined start timing of said apparatus reaches a predetermined time.
 13. An apparatus according to claim 12, wherein said division test write processing unit determines an optimum light emitting power by executing the test processes in a lump by a first upper command, sets a valid time for making an adjustment of said optimum light emitting power unnecessary on the basis of the elapsed time until the present time, inhibits the test process for the upper command until the elapse of a time of a predetermined rate of said valid time, and allows the division to be executed for the upper command for said valid time from said predetermined rate time.
 14. An apparatus according to claim 13, wherein said division test write processing unit inhibits said test process in a time zone that is less than 90% of said valid time and permits said test process in a time zone exceeding 90% of said valid time.
 15. An apparatus according to claim 13, wherein when the elapsed time exceeds said valid time on the way of an execution stage of said test process, said division test write processing unit executes the remaining test processes in a lump by a next upper command.
 16. An apparatus according to claim 13, wherein said division test write processing unit sets the valid time so as to be long step by step in proportion to the elapsed time from said start timing.
 17. An apparatus according to claim 2, wherein said division test write processing unit validly operates and executes said test processes after the elapsed time from a predetermined start timing of said apparatus exceeds a predetermined time.
 18. An apparatus according to claim 2, wherein said division test write processing unit detects a temperature in the apparatus every predetermined time and allows said test processes to be executed when a temperature difference between the detected temperature and a previous detection temperature exceeds a predetermined temperature.
 19. An apparatus according to claim 18, wherein when said temperature difference exceeds an upper limit temperature that is higher than said predetermined temperature during an executing stage of said test process, said division test write processing unit allows said test processes to be executed in a lump.
 20. An apparatus according to claim 19, wherein when the temperature difference between the previous and present dividing processes exceeds said predetermined temperature during the test process, said division test write processing unit cancels the processed numbers and processing results up to the previous time and again executes the test processes from the beginning. 